Mesut Özil will miss the next 10 to 12 weeks with a partial knee ligament tear in his left knee.
Özil suffered the injury during Arsenal's 2-0 loss on Sunday to Chelsea. Özil didn't leave the match, but reported the problem to Arsenal's medical staff after the game.
The German Federation sent Özil for a scan, which revealed the tear.
Özil, who missed six weeks towards the end of last season with a hamstring injury before recovering to play his part in Germany’s World Cup triumph, joins a lengthy injury list at Arsenal.